investigator

investigator — noun

1. someone employed to look into crimes, accidents, or suspicious events to discove

1.nounB1
Definition

someone employed to look into crimes, accidents, or suspicious events to discover the true facts — for example, a police officer gathering evidence at a burglary scene or an insurance agent checking whether a claim is genuine.

Example

Police investigators spent hours collecting fingerprints and DNA samples from the apartment.

collocation: police investigators

A private investigator named Hassan tracked down the stolen painting in a small town.

collocation: private investigator

Common collocations
  • police investigator
  • private investigator
  • lead investigator
  • chief investigator
  • fire investigator
  • federal investigator
Synonyms
  • detective

    more specific — usually a police officer who investigates crimes, whereas investigator covers a broader range of settings

  • inspector

    often a rank within a police force or an official who checks compliance, e.g. a health inspector

  • examiner

    less formal and less authoritative; can refer to anyone who looks closely at something

Grammar Patterns

investigator + of + noun phrase

compound: [adjective] + investigator

Usage Note

Often used in compound job titles such as police investigator, private investigator, or fire investigator. Unlike detective, which in many places refers specifically to a police officer, investigator can describe a wider range of roles including insurance, fraud, and workplace-safety positions.

Common Mistakes

The investigator examined the patient for symptoms.
The doctor examined the patient for symptoms.
an investigator looks into crimes and incidents, not medical conditions.
She hired an investigator to cook dinner.
She hired a private investigator to follow her husband.
the word refers to factual inquiry, not general services.

2. a person who carries out experiments or systematic studies as part of scientific

2.nounB2
Definition

a person who carries out experiments or systematic studies as part of scientific or medical research — for example, a biologist testing a new vaccine or a psychologist running a study on sleep patterns.

Example

Medical investigators are testing a new drug that could help lung cancer patients.

collocation: medical investigator

The principal investigator on the project presented the results at a conference in Berlin.

collocation: principal investigator

Common collocations
  • principal investigator
  • medical investigator
  • research investigator
  • clinical investigator
  • team of investigators
Synonyms
  • researcher

    broader — can include scholars who do not carry out hands-on experiments (e.g. historians); investigator emphasises empirical or clinical inquiry

  • scientist

    more general — a scientist may teach or theorise; an investigator is actively gathering data

  • experimenter

    narrower — one who conducts a specific experiment, not necessarily a long-term research programme

Grammar Patterns

investigator + into + noun phrase

investigator + on + noun phrase

principal + investigator

Usage Note

Common in formal academic and medical writing; principal investigator (PI) is the standard title for the researcher who leads a funded project. In some contexts investigator is used interchangeably with researcher, though investigator emphasises active, hands-on inquiry.

Common Mistakes

The scientific investigator arrested the suspect.
The police investigator arrested the suspect.
a scientific investigator does not have law-enforcement authority.

Word family

Synonym discussion

Sense: noun/1

Investigator, detective, inspector, examiner, and inquirer all refer to someone who looks into something, but they differ in scope and formality. Investigator is the broadest term: it covers anyone whose job is to uncover facts, whether in law enforcement, insurance, or workplace safety. Detective is narrower — it specifically means a police officer who investigates crimes, often in plain clothes. Inspector implies an official rank or someone who checks compliance with rules (e.g. health inspector, building inspector). Examiner focuses on close scrutiny of an object or document, often without the authority of an investigator — a bank examiner reviews financial records, but does not interrogate suspects. Inquirer is the most general and least formal, simply meaning someone who asks questions, and it rarely appears in professional job titles. For everyday use, investigator suggests professional training and official authority, whereas detective is limited to police contexts and examiner is limited to document or compliance checks.

detective ↗inspector ↗examiner ↗inquirer

Common collocations

Nouns

Adverbs

Phrases

  • team of investigators
  • investigator in charge
  • investigator on the case

Prepositions

Etymology

LatinEnglish

Investigator comes from Latin investigare, meaning 'to track down' or 'to follow the footprints of'. The word breaks into in- (toward) and vestigium (footprint or track), so the original image is of someone literally following footprints to find a person or animal. It entered English in the early 1500s, first used for legal and criminal inquiries, and later extended to scientific research.